Field of Invention
The present invention relates to a method of labeling glycoproteins on a surface and an application thereof producing the same. More particularly, the present invention relates to a method of traceless labeling glycoproteins on the solid surface without altering the composition of mono/oligo-saccharides and an application thereof.
Description of Related Art
The use of synthetic molecules to label and track proteins of interest accelerates progress in the studies of protein function, localization, and structure, which are closely related to biological significance. Synthetic chemistry is a central component of modern chemical biology, providing tailored molecules that can be used for the precise, covalent modification of biomolecules of interest. Compared to protein fusion-based methods using green fluorescent protein or affinity protein tags, the chemistry-oriented strategy with small organic probes better conserves the native structures of target proteins and reduces their loss of biological activity. Therefore, the development of chemical methods of protein labeling can certainly reduce the undesired alteration of important tertiary structures of the protein. The techniques can be used in studies of protein-ligand, protein-protein, and protein-biomolecule interactions and are especially suitable in complex biological environments.
However, with conventional chemical methods for protein labeling, such as the formation of an amide bond, Schiff base, or other covalent conjugations, lack of regioselectivity and multiple reaction sites are always observed between probe molecules and the endogenous residues of proteins, therefore leading to ambiguous results. Accordingly, a substantial improvement of the chemical probes used in the site-selective modification of target proteins must be accompanied by a combination of bioorthogonal chemistry and metabolically or genetically incorporated chemical entities. However, the use of molecular biology techniques such as the incorporation of noncanonical amino acids or genetic engineering for advanced bioorthogonal conjugation may induce to a change in protein activity. Thus, a need is emerging for a new method for the site-selective labeling of endogenous proteins in their native habitats. To this end, some researchers proposed a method termed ‘activity-based protein profiling’ (ABPP), which allows the characterization of several enzymes in their active states through protein activity-directed recognition. Proteins of interest can be selectively labeled and isolated by this method; however, the chemical probes may inactivate the labeled proteins.
It is believed that more than 50% of known proteins are subject to post-translational glycosylation, and the glycosylation process plays a key role in the recognition events involved in cell development, immunology, and cancer biology. Glycosylation in protein modification refers to the covalent attachment of a diverse set of one or more sugar molecules to a protein; the sugar part of the glycoproteins thus formed is termed a “glycan”. Certainly, glycoproteins are involved in many important biological processes; however, only a few glycan-based targeting strategies are currently available, and most of them result in an irreversible alteration of native glycan structures. The structural alteration of a glycan always results in a considerable loss of its biological significance.
There is, however, a growing need for new methods of glycoprotein labeling and enrichment is emerging, for overcoming all issues of conventional glycoprotein labeling methods and accelerating the understanding of glycoproteins and their role in the advanced regulation of the cell life cycle.